In matters of military contingency, the expected, precisely because it is expected, is not to be expected. Rationale: What we expect, we plan and provide for; what we plan and provide for, we thereby deter; what we deter does not happen. What does happen is what we did not deter, because we did not plan and provide for it, because we did not expect it.
Sir Michael Quinlan, quoted here.
Channeling Keynes…
I was just listening to Donald Kagan on Yale open courseware discussing the Mycenaens building citadels several miles from the sea shore because you never know what might sail up during the night and appear in your harbor while land invaders create a warning in their wake with refugees.